Pneumatic piano-action.



A. G. GIILBRANSEN.

PNEUMA'IIG PIANO AG'IION.

APPLICATION FILED JAN. 3, 1910.

Patented May @1911.

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AXEL G. GULIBRANSEN, OF CHICAGO, ILLINOIS, ASSIGNOR T GULBRANSEN "DICKINSON GQILVIPANY, O1? CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PNEUMATIC PIANO-ACTION.

Specification of Letters Patent.

Patented May 9, infill.

Applicationfiled January 3, 1910; Serial no. 536,122.

ings, forming a part of this specification.

My invention relates to pneumatic pianos and other pneumatic instruments, and its object is the production of a structure where- .in the parts may be rigidly secured together in an improved manner and wherein air leakage may be reduced to a minimum, the efficiency of the instrument being thereby correspondingly lncreased.

As is well known in the art, pneumatic :30 pianos or pneumatic piano-playlng mechanisms comprise, among other parts, a channel board, and "a considerable number of pneumatic actions or action members, one of the latter being provided foneach of the keysof the piano which it is desired to use.

Each of these pneumatic actions or action members comprises valve mechanism and a bellows, the movable membei of which is connected, in some suitable manner, with one of the abstract rods of thepiano proper.

The channels provided in thecliannel board, which is usually made three-ply so as to facilitate construction, provide means for properly connecting" the pneumatic act-ions or the parts thereof with the feeder bellows,

or the atmosphere by way of the tracker board, whichever the case may be. It is of course apparent that there should be an ab solutely tights-joint between the pneumatic 'a ctions ano. the channel-board, and it has been attempted to secure this result 111 many different ways. The usual practice of the art, and probably the most efficient one, 1s to place a layer of soft material, such as leather or rubber, between the back of the pneumatic action and the chanrvl board, and to secure the action in plane y means of wood screws passing through part of the board and into the frame of the action. It

51) is of course apparent that the joint can be made tight by tightening" the wood screws, but it has been found that the wood of the PllOll'tl'ltll'lC frame yields to the action of the wood screw before the intermediate leather 55 or rubber has been compressed to the desired extent. My invention is directed toward the elimination of this difliculty and provides means whereby a machine screw may be used, and whereby the strain on the frame of the pneumatic action is distributed over a greater area than when a wood screw is employed, and, specifically, over an area quite transverse to the pull exerted when the screw is manipulated.

My invention is embodied in the structure illustrated in the accompanying drawings, in wh ch- Figure 1 illustrates a partial side view of a piano, the end of the casing bcing.re moved to disclose the channel board, the pneumatic actions and the associated abstract rods. Fig. 2 is a top View of a portion of the channel board and a portion of one of the pncumatics, showing the means whereby the two are securely connected, and Fig. 3 is a sectional view on the line 33 of Fig. 2.

Like reference characters are applied to the same parts throughout the various figures.

In Fig. 1 the piano casing is shown at 4, the keyboard being illustrated at 5, and the cover therefor at 6. The piano keys are shown at 7 7, are pivotally hung at-8, and, by means of abutment members 9, are suitably connected with corresponding abstract rods 10. The channel board isshown at 11, being disposed immediately in front of the lower ends of the abstract rods, and is made up of the plies 12, 1?.- and 14-, the ply 13 being a frame to form a chamber and the ply 14 being provided with various openings to connect with. the pneumatic actions. The pneumatic actions are illustrated at 15, 15, are arrai'lged in tiers or rows, and are --staggered to correspond with the disposition of the abstract rods. As clearly shown 1n Fig. 3, each of the pneumatlcs comprises a frame 16, in which are provided the chan nels and valve chambers 17, 18 and 19, re: spectively, as indicated 1n dotted lines The particular arrangement of channels and valve does not concern this invention, and specific reference ,will not bemade thereto. prises the action bellows 2 0, the movable The pneumatic action also commember 21 of which is disposed to engagethe abutment pieces 22, 22 on the abstract rods 10. It is apparent that when the an is exhausted from the action bellows 20,

the member 21 will rise to operate the associated abstract rod precisely as if the corresponding hey had been depressed. In orour to provide a tight joint between the pneumatic action and the channel board, layer leather, rubber or similar co1n- .ressible material is interposed between hese parts, clearly shown in the various "guises. The pneumatic actions are held pen the charmel board. by means of iassing directly through the ply 1 and ntu the pneumatic action :traiue- In the prior art was the custom to employ Wood screws but, as has oer-ore been stated, it has bee.u.- 'tound that these .wood screws could not be tightened to such an extent to make the joint between the pneumatic aclion and the channel board 'i nt ini ht be desirable. i-llustrateu various figures, and 2 and 3 pm larly i provide a metallic member 24%, conveniently in the form. of a pin. of substantial dimensions, disposed with a sou a corresponding opening drilled in the frame 1'6 ol the pneuuifif These pins are provided in such position that they do not interfere with the cha i Jr,

01: valve chambers in. the pneumatic action,

and shown in 2, are provided at each side of the structure a considerable distance from the r, there will be no possibilw' oii their l. nu the frame For each member l inc screw 25 provided, this maclum 51. u passing through ply 3 -3: of the beard and through an opening in the frame flll, so that it may" have 'li lzrcadcd engagement with a transverse o )(Pfllb'l 26 in member 24. A. Washer 27 is preferably interposed between the head. of the machine screw 25 and the surface of the oly' board or obvious purposes. It will now be seen that the threadecl engagement is had. with a metallic member properly machined for that purpose, and that the i l or; thereon when the screw is turner. distiibuted over a considerable most of 'WlllCl'l is transverse to direction of? pull. it is further apparent that tightening this machine screw 25 will result in the compression of the washer or gasket member 23, and in the consequent provision of a tight and efficient joint.

The particular construction of the chan nel board is not concerned in the present invention. However it may be noted that in the embodiment shown the ply is really constituted the channel board he other plies iornnng an associated chamber. The

l matic action frame to said channel board.

plies 12 and 13 may be removed bodily from the ply 14, any suitable means of attachment being employed, so as to give access to the heads of all the screws I claim as new and desire to secure by Letters Patent:

1. In an automatic piano, a channel. board, a pneiunatic action, a metal rod sccurcly carried by said. pneumatic action, and a screw passing through said channel board and. substantially at right angles to said rod and having threaded engagement with said rod to clamp said. pneumatic action to said channel hours.

2. in an automatic piano, a channel board, a pneumatic action ironic metal rod mubcddcd in said frame, and. a machine screw passing through said channel board substantially at right 2 es to said rod and having threaded engag ment with said. rod to clamp pneumatic action frame to said channel board.

,frune, a metal rod scour y embedded in said irani and a r chirtiu cg tliu'ough said channel SPILL substan iy at right angles to Hi rod'and. having tnreao ed engagement with rod i ereby the pull of. the screw exerted over the front urea ol? 'tlie rod to clamp said pneumatic acflame to said channel board.

. an. automatic piano, a channel. heart, a wooden pneumatic action frame, a metal rod securely en-ibcdded in said. frame near the front end thereof and parallel. to the plane of said channel board, and a macliine screw passing through said channel board substantially at right angles to said rod and having threaded. eiwageroent with said rod whereby the pull. of the screw is exerted over the front area of said rod to clamp the pneumatic action frame to the channel board.

5. In an automaticpiano, a wooden mnncl lormni, a Wooden pneun'r frame, a metal rod securely carr irueumatic action frame and a screw lassing through said channel board trans verse] y oi saidacd and having threaded engagement with said rod to clamp said pneuln witness whereof, I hereunto subscribe my name this 29th day of December, A. D.

A X'llli Gr. GULBRANSEN.

il iiuessesz ARTHUR H. llou'r'rciiini, LEONARD W. Novunonu. 

